Rotary head for sanding machines



Nov. 9, 1948.

J; C. HAMMONTREE ROTARY HEAD FOR SANDING MACHINES 2 Sheets-Sheet I FiledDec. 5, 1947 FIG-3 INVENTOR. J. c. HAMMONTREE F/GZ Attorneus Nov. 9,1948- J. c. HAMMONTREE ROTARY HEAD FOR SANDING MACHINES 2 Sheets-Sheet2.

Filed Dec. 5, 1947 INVENTOR. J. C. HAMMON TREE FIG. /0

Attorneys Patented Nov. 9, 1948 UNITED STATES PATENT OFMCE 4 Claims.

My invention relates to a power operated rotary head for sandingmachines.

An important object of the invention is to provide a head for sandingmachines, wherein the sand paper sheet or disc can be changed oradjusted Without disassembling the parts of the head or removing anyscrews or the like.

A further object of the invention is to provide a sanding head whereinthe sand paper is clamped between two members and held in place byspring tension, thus eliminating the need for attaching screws, andproviding a full circular sanding surface.

A further object of the invention is to provide a sanding head adaptedto be mounted upon the armature shafts of portable or stationary motors,and which is extremely simplified in construction, durable andinexpensive to manufacture.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings, forming a part of this application, and inwhich like numerals are employed to designate like parts throughout thesame;

Figure 1 is a central vertical section through the sanding headembodying the invention, and

showing the same mounted upon the armature.

shaft of an electric motor, parts in elevation.

Figure 2 is a plan view of a sanding sheet or disc removed.

Figure 3 is a side elevation of a locking sleeve removed.

Figure 4 is an end elevation of the same.

Figure 5 is an end elevation of a sanding disc.

Figure 6 is a side elevation of the same.

Figure '7 is an elevation of a clamping disc.

Figure 8 is a side elevation of the same.

Figure 9 is a fragmentary side elevation of the clamping disc, taken atright angles to Figure 8.

Figure 10 is a fragmentary end elevation of the clamping disc.

In the drawings, where for the purpose of illustration is shown apreferred embodiment of the invention, the numeral l5 designates anelectric motor, having an armature shaft l6, including a reduced endextension l1.

Detachably mounted upon the reduced extension l1, and rigidl securedthereon, by means of a set-screw I8, is a sanding disc I 9, including aspindle 20. The spindle is cylindrical and includes a reducedscrew-threaded extension 2| forming a lateral annular shoulder 22, andhaving a central axial bore or opening 23 to receive the extension I1.The spindle 20 is disposed at the center of the disc H] which iscircular, rigid and fiat. The disc I9 is rounded at its peripheral edge24. The disc I9 is integral With the spindle 20, and disposed at rightangles to the same. The top of the set-screw i8 does not project abovethe outside diameter of the extension 2!.

Mounted upon the screw-threaded extension is a locking sleeve 25. Thislocking sleeve is internally screw-threaded and cylindrical at its endadjacent to the shoulder 22 as at 26. The locking sleeve 25 includesdiametrically oppositely disposed projections or pins 21, which projectradially from the sleeve. The end 23 of the sleeve 25 remote from theshoulder 22 is hexagonal, as shown. The outer end of the sleeve 25 isadapted to engage the shoulder 22, when the sleeve is in a locked orclamping position. In such position, the set-screw I8 is disposed beyondthe opposite end of the sleeve 25, as shown.

v with, and disposed at the center of the disc The sleeve 30 iscylindrical and tubular and. engages over the spindle 20 and cylindricalend 25 of sleeve 25, as shown. The sleeve 30 is slidable upon thespindle 20 and end 26. l

The sleeve 30 has an inner annular end 3i having diametricall oppositelyarranged cylindrically curved radial recesses 32, adapted to form seatsfor the pins 21 of sleeve 25, when such sleeve is in the lockingposition. Adjacent to the recesses 32 and spaced angularly slightltherefrom, Figure l0, and formed in the end 3| and side wall of thesleeve 3!] are spiral slots 33. which terminate near the longitudinalcenter of the sleeve to, as shown. The pins 2! are adapted to slidablyenter the spiral slots 33 when the sleeve 25 is in the unlockedposition. The forward face of the clamping disc 29 is slightly concave,as shown at 34, so that onl a relativel narrow circumferential portion35 of the disc 29 engages the inner flat surface of the sanding disciii. The disc 29 is somewhat resilient due to its concavity.

A circular sandpaper sheet 36, or the like, having a scalloped marginaledge, forming triangular teeth 31, is mounted upon the forward face ofthe sanding disc 19. The triangular teeth i! are folded around therounded edge 24 and arranged between the inner face of the disc 19 andthe narrow annular portion 35 of the clamping disc 29. The teeth 31 areprovided to prevent wrinkling of the sandpaper sheet 36. edge 24prevents possible cutting of the sandpaper The roundedsheet. The entireforward or working face of the sanding disc I9 is covered by thesandpaper sheet 36, as shown.

In use, the sanding head is applied to the armature shaft of the motor,as shown in Figure l. The set-screw i8 is tightened, and the head willrotate with the armature shaft. With a sandpaper sheet 36 in place, asin Figure 1, the locking sleeve is screwed to the left, Figure 1, untilthe shoulder 22 is engaged. The ins 121 are 'now engaged in the recesses32 of the sleeve 30, and'the clamping disc 29 is locked in tightclamping engagement against the sanding disc l9, to secure the sheet 36in place. The disc-29 is slightly resilient, as stated, and exerts ayielding force upon the scalloped edge of the sandpaper sheet.

When it becomes necessary to change the sandpaper sheet, it isunnecessary to disassemble the sanding head. A wrench or the like isapplied to the hexagonal end 28 of locking sleeve 25, and the sleeve isunscrewed sufficiently for the ;.pins 2] to disengage from within therecesses 32 When this occurs the .sleeve 2st) ,is turned slightly uponits longitudinal axis, :until the pins 21 engagein the spiral slots 33,at the sleeve end 31. The sleeve 33 is now turned further, and due tothe action of 1c pins 21 in thespiral slots 33, theisandng disc 29 maybe readilyshifted axially to a position like that shown bydotted linesin Figure 1. Abundant space is thus provided to change the sandpapersheet 36. The sleeve 36 is thenturned in the opposit-e direction, andthe disc 29 will advance toward the clamping ,position. The pins '2 willleave thespiral slots .33, andare again engaged in the recesses 32. Thelocking sleeve is now tightened against the shoulder 22, and the newsandpaper sheet 36 is securely-clamped in .place.

It is to be understood that the form of the invention, herewith shownand describ.ed,is'to :be taken as a preferred example of the same, andthat various changes in the shape, size and :arrangement of parts mayberesorted to. without departing from the spirit of the invention -or {thescope of the subjoined claims.

Having thus-described the invention, I claim:

l. A rotary head forsandi-ng machines including a motor having anarmature shaft, such head comprising a sanding disc :mountednpon thearmature shaft for rotation therewith, thesanding disc including aspindle having ascrew-threaded extension, clamping disc .slidably:monnted upon the spindle and adapted to engage the sanding disc andincluding asleeve havinglan end recess and spiral slot, and alockingsleevemountedupon the screw-threaded extension and including a part toalternately enga ein the end .recess and spiral slot.

2. A rotary head for sanding. machines. includsion and includingprojections to alternately en- .gage in the recesses and the spiralslots.

' 3. A rotary head for sanding machines includmounted upon the armatureshaft for rotation therewith, said sanding disc including a cylindricalspindle having a screw-threaded extension provided withan opening toreceive the armature shaft therein, the screw-threaded extension forminga shoulder, a clamping disc carried by the spindle and slidably mountedthereon and adapted to he clamped against the sanding disc and to moveaway from the same, the clamping disc being resilient and having aconcave face adjacent to the sanding disc, the clamping disc including acylindrical sleeve to engage over the spindle and having end recessesand spiral slots in itssides and extending through its end and aninternally screwethreaded locking sleeve mounted upon the screw-threadedextension and including lateral pins to alternately engage in therecesses and spiral slots, the locking sleeve engaging against theshoulder when in the locking position.

4. A rotary head for sanding machines including a motor having anarmature shaft, the head comprising a substant ally circular and flatsandingdisc mounted upon the armature shaft for rotation therewith, saidsanding disc includinga spindle having a screw-threaded extension, ,aclamping disc mounted upon the spindle and slidable thereon and adaptedto he vclamped against the sand ng disc the clampinr disc including asleeve to engage over the spindle and having end recesses and spiralslots in its side wall, a locking sleeve mounted upon the screwthreadedextension and including pins to engage in the spiral slots and recesses,and a circular sanding .sheet having a scallopededge, the sanding sheetcovering the forward face of the sanding disc and the scalloped edgebeing clamped between the sanding disc and clamping disc.

JACK C. HAMMONTREE,

,No references cited.

